This application claims the benefit under 35 U.S.C. §119(a) of Korean Patent Application No. 2004-4564, filed on Jan. 24, 2004, in the Korean Intellectual Property Office, the entire disclosure of which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to an image forming device. More particularly, the present invention relates to a device and method for managing status information related to a consumable for an image forming device by using memory included in the consumable.
2. Description of the Related Art
Generally, a photocopy-type image forming device generates an electrostatic image on a photosensitive medium such as a photosensitive drum or a photosensitive belt, and develops the electrostatic image by transferring toner of a predetermined color onto paper.
FIG. 1 schematically shows a conventional image forming device 100.
The conventional image forming device 100 comprises a developing unit 110, a transferring unit 160, and a fixing unit 150. To generate a predetermined image, the developing unit 110 supplies toner to an electrostatic image formed on a photosensitive medium 115 by a laser scanning unit 180. The developing unit 110 comprises a developing roller 170 installed to be partially soaked into toner in a toner container 175 and to rotate with respect to the photosensitive medium 115. The transferring unit 160 is installed to be located on a side of paper with respect to the photosensitive medium 115 and transfers the image formed on the photosensitive medium 115 onto the paper. The fixing unit 150 presses the image transferred onto the paper by the transferring unit 160 by heat and/or pressure. The transferring unit 160 can also perform the fixing operation when connected to a predetermined heat source.
Additionally, the image forming device 100 comprises a paper cassette 130, a roller 135, which picks up paper from the cassette and supplies the paper to a path adjacent to the transferring unit and the photosensitive medium. The image forming device 110 further comprises a paper ejector 190, which ejects paper on which an image is formed and fixed.
Consumables used in the conventional image forming device comprise four toner cartridges (Yellow, Magenta, Cyan, Black), a middle transferring belt, and a photosensitive drum. Each of the consumables is identified by using an identification KEY resistor. It is impossible to identify the remaining lifetime of a toner cartridge when no sensor is provided. The following operations are used to estimate the remaining lifetime of consumables.
At first, lifetime data is initialized in a first non-volatile memory included in the image forming device when a consumable is replaced. Then, a printout number count is stored in the first non-volatile memory and the amount of consumable use is calculated by adding dot numbers of the image data.
In the case of the middle transferring belt and the photosensitive drum, the amount of consumable use is calculated by using image printout numbers, which is based on value stored in the printout counter. Usually, the middle transferring belt and the photosensitive drum can print more than 50,000 sheets of paper, and the printout counter can be cleared after replacing the toner cartridge. Alternatively, a user can directly manipulate the counter to clear it.
FIG. 2 illustrates a conventional consumable included in an image forming device.
As noted above, the consumable can either be a toner cartridge, a middle transferring belt, or a photosensitive drum. The consumable includes identification information and provides it to the image forming device.
FIG. 3 schematically shows a conventional consumable in conventional image forming device.
The consumable 200 in FIG. 3 is identified by key resistors R1 and R2. The image forming device 100 uses a detection driver 105 to detect the consumable 200, and stores the status information of the consumable in a memory 109. Preferably, an ASIC 105 acts as a central controller.
In the image forming device 100 in FIG. 3, a KEY detection signal is differentiated based on the resistors R1 and R2. That is, when the image forming device 100 divides a pull-up resistor and the key resistor R2 of the consumable 200, a different voltage is sensed based on the resistance of the key resistor R2.
FIG. 4 illustrates a KEY detection signal of a consumable 200 included in a conventional image forming device 100.
In FIG. 4, the X axis denotes an output voltage and the Y axis denotes a resistance R2. In this particular example, the resistance of the pull-up resistor can be equal to 47 Kohm and Vcc is equal to 3.3V. As shown in FIG. 4, the output voltage is differentiated based on the resistance R2, which identifies the KEY detection signal.
FIG. 5 is a flowchart of a conventional management method of a consumable in an image forming device.
The method in FIG. 5 includes detecting an installation status and determining whether the expected lifetime is exceeded. Further, the remaining lifetime is calculated when the lifetime is not exceeded.
However, the conventional management method is subject to noise due to analog voltages since there are a plurality of consumables included in the image forming device. Noise interference can result in misreading of the status information. Furthermore, since the reading error is not negligible since the amount of the consumable used is calculated using dot numbers of image data in a software program, it is nearly impossible to estimate the remaining lifetime when a second-hand consumable is installed. Also, the remaining lifetime cannot be estimated when the memory included on the image forming device is erased due to a replacement of a mainboard.
Therefore, reliable methods and devices for easily managing status information of a plurality of consumables are needed.